1. Field of the Invention
The present invention relates to an emission deterioration informing device that informs deterioration of exhaust emission.
2. Description of Related Art
Among spark ignition internal combustion engines, in a port injection internal combustion engine that injects fuel to an intake port, most part of the injected fuel adheres to an inner wall surface of the intake port once. Then, the fuel evaporates and is suctioned into a combustion chamber, in which the fuel combusts. Therefore, even if actual injection timing somewhat deviates from target timing, there is little or no influence on exhaust emission.
In contrast, in a direct injection internal combustion engine that injects the fuel directly into the combustion chamber, the exhaust emission deteriorates largely even if the actual injection timing deviates from the target injection timing only slightly (refer to Patent document 1 (JP-A-2006-283737)). Therefore, when a deviation amount of the actual injection timing from the target injection timing is large and exceeds a predetermined threshold value, it is required to inform a driver of the deterioration of the exhaust emission by operating an emission deterioration informing device such as a warning light.
However, depending on an operating state of the internal combustion engine, there is a case where the exhaust emission does not deteriorate largely even if the above-mentioned deviation amount is large. It is not appropriate to light the warning light also in such the case. It is preferable to restrict the lighting of the warning light to the necessary minimum.